This application is a request for an ADAMHA RSDA Level II award. The long-term objective of the proposed research is to understand how the brain establishes emotional memories. In previous studies, pathways that are essential for the classical conditioning of emotional memories by pairing an acoustic conditioned stimulus with an aversive unconditioned stimulus were identified. An essential pathway in this circuitry involves the relay of acoustic information from the thalamus to the amygdala. The proposed experiments will attempt to identify cellular mechanisms in the thalamo-amygdala pathway that underlie emotional conditioning. In particular, the focus is on synaptic interactions between amygdala neurons and their inputs from auditory processing areas of the thalamus. The goals are to determine whether the excitatory amino acid, glutamate, is present in the pathway and, if so, to determine whether this substance contributes to neurotransmission, synaptic plasticity and emotional learning. To achieve these goals, light and electron microscopic anatomical studies, unit recording neurophysiological studies, and behavioral studies will be performed. The results of these experiments should begin to take our understanding of emotional learning to the level of detailed neural circuits and their synapses and should help in the understanding and treatment of emotional disorders.